package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.dto.Result;
import com.hmdp.dto.ScrollResult;
import com.hmdp.dto.UserDTO;
import com.hmdp.entity.Blog;
import com.hmdp.entity.Follow;
import com.hmdp.entity.User;
import com.hmdp.mapper.BlogMapper;
import com.hmdp.service.IBlogService;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IUserService;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.SystemConstants;
import com.hmdp.utils.UserHolder;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ZSetOperations;
import org.springframework.stereotype.Service;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.List;
import java.util.Set;
import java.util.stream.Collectors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class BlogServiceImpl extends ServiceImpl<BlogMapper, Blog> implements IBlogService {

    @Resource
    private IUserService userService;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private IFollowService followService;


    @Override
    public Result queryHotBlog(Integer current) {
        // 根据用户查询
        Page<Blog> page = query()
                .orderByDesc("liked")
                .page(new Page<>(current, SystemConstants.MAX_PAGE_SIZE));
        // 获取当前页数据
        List<Blog> records = page.getRecords();
        // 查询用户
        records.forEach(blog -> {
            queryBlogUser(blog);
            isBlogLiked(blog);
        });
        return Result.ok(records);
    }

    @Override
    public Result likeBlog(Long id) {
        Long userId = UserHolder.getUser().getId();
        String key = RedisConstants.BLOG_LIKED_KEY + id;
        // 由于 Zset 没有判断是否存在的，只能查分数，分数存在则存在
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        if (score == null) {
            // 可以点赞
            // 修改点赞数量
            boolean update = update().setSql("liked = liked + 1").eq("id", id).update();
            if (update) stringRedisTemplate.opsForZSet().add(key, userId.toString(), System.currentTimeMillis());
        } else {
            boolean update = update().setSql("liked = liked - 1").eq("id", id).update();
            if (update) stringRedisTemplate.opsForZSet().remove(key, userId.toString());
        }
        return Result.ok();
    }

    @Override
    public Result queryBlogById(String id) {
        Blog blog = getById(id);
        if (blog == null) {
            return Result.fail("笔记不存在");
        }
        queryBlogUser(blog);
        isBlogLiked(blog);
        return Result.ok(blog);
    }

    private void isBlogLiked(Blog blog) {
        UserDTO user = UserHolder.getUser();
        if (user == null)
            return;
        Long userId = user.getId();
        String key = RedisConstants.BLOG_LIKED_KEY + blog.getId();
        Double score = stringRedisTemplate.opsForZSet().score(key, userId.toString());
        blog.setIsLike(score != null);
    }

    private void queryBlogUser(Blog blog) {
        Long userId = blog.getUserId();
        User user = userService.getById(userId);
        blog.setName(user.getNickName());
        blog.setIcon(user.getIcon());
    }

    @Override
    public Result queryBlogLikes(String id) {
        String key = RedisConstants.BLOG_LIKED_KEY + id;
        // 查询前五条
        Set<String> range = stringRedisTemplate.opsForZSet().range(key, 0, 4);
        if (range == null || range.isEmpty()) {
            return Result.ok();
        }
        List<Long> ids = range.stream().map(Long::valueOf).collect(Collectors.toList());
        // 根据用户id查询用户
        List<UserDTO> list = userService.lambdaQuery().in(User::getId, ids)
                .last("order by field(id, " + StrUtil.join(",", ids) + ")")
                .list()
                .stream()
                .map(user -> BeanUtil.copyProperties(user, UserDTO.class))
                .collect(Collectors.toList());
        return Result.ok(list);
    }

    @Override
    public Result saveBlog(Blog blog) {
        // 获取登录用户
        UserDTO user = UserHolder.getUser();
        blog.setUserId(user.getId());
        // 保存探店博文
        boolean save = save(blog);
        if (BooleanUtil.isFalse(save)) {
            return Result.fail("新增笔记失败！");
        }
        // 查询笔记作者的所有粉丝
        List<Follow> list = followService.lambdaQuery().eq(Follow::getFollowUserId, user.getId()).list();
        list.forEach(follow -> {
            Long userId = follow.getUserId();
            String key = "feed:" + userId;
            stringRedisTemplate.opsForZSet().add(key, blog.getId().toString(), System.currentTimeMillis());
        });
        // 推送笔记id给所有粉丝
        // 返回id
        return Result.ok(blog.getId());
    }

    @Override
    public Result queryBlogOfFollow(Long max, Integer offset) {
        // 1. 第一步，找到收件箱---需要当前用户。
        Long id = UserHolder.getUser().getId();
        String key = RedisConstants.FEED_KEY + id;

        // 使用了 Redis 中的有序集合（Sorted Set）进行范围查询，并按照分数（Score）进行降序排列。
        Set<ZSetOperations.TypedTuple<String>> typedTuples = stringRedisTemplate.opsForZSet()
                .reverseRangeByScoreWithScores(key, 0, max, offset, 2);

        // 非空校验
        if (typedTuples == null || typedTuples.isEmpty()) {
            return Result.ok();
        }

        // 2. 解析数据（blodId、score、offset）
        ArrayList<Long> list = new ArrayList<>();
        long minTime = 0;
        int os = 1;
        for (ZSetOperations.TypedTuple<String> typedTuple : typedTuples) {
            list.add(Long.valueOf(typedTuple.getValue()));
            long time = typedTuple.getScore().longValue();
            if (time == minTime) {
                os++;
            } else {
                minTime = time;
                os = 1;
            }
        }

        String str = StrUtil.join(",", list);
        List<Blog> blogs = query().in("id", list).last("order by field(id," + str + ")").list();
        blogs.forEach(blog -> {
            // 查询blog有关用户
            queryBlogUser(blog);
            // 查询博客是否被点赞
            isBlogLiked(blog);
        });

        // 3. 根据ID，封装数据并返回。
        ScrollResult scrollResult = new ScrollResult();
        scrollResult.setList(blogs);
        scrollResult.setOffset(os);
        scrollResult.setMinTime(minTime);
        return Result.ok(scrollResult);
    }
}
